1. Technical Field of the Invention
The present invention relates to a cellular phone that can indicate the time-of-day (hereinafter referred to as time) and its base station, and, more particularly, to a cellular phone suitable for displaying the local time in a area where a recipient uses a cellular phone.
2. Description of Related Art
A cellular phone equipped with a clock circuit and a display screen and capable of displaying the time has come into wide use. However, in such cellular phone, the time displayed is only the time at the place where the user or calling party exists, and the time at a receiving end or a recipient could not be displayed. Accordingly, in the case of making a phone call in the United States where multiple time zones are provided within the country and making an international phone call, calls have been made without considering a time difference. As a result, such inconvenience has occurred that business could not be handled because the call was made not within the working hours of the receiving end.
As art that solves this problem, for example, as disclosed in JP-A No. H6-276262, there is a technique for calculating the local time at the receiving end from the telephone number of the receiving end and the local time at a caller. When a caller makes an international call, this technique identifies a country or an area of a recipient from the high-order digits within the international long-distance telephone number identification part of the recipient's telephone number and calculates the time difference between the identified country or area and the caller, and then calculates and displays the local time at the recipient, using the clock (matching the local time at the caller) inside the cellular phone and the calculated time difference.
In prior art, the local time can be displayed on the cellular phone. However, this technique is effective only when the receiving end is a fixed-line telephone, but any technique that is effective for making a call to the cellular phone is not disclosed.
In addition to the rapid spread of a cellular phone, due to an international roaming function that enables communication for a country where the services of the same method is being performed even if the cellular phone is carried out abroad, the probability that the recipient's phone is a cellular phone is inclined to increase more and more. This international roaming function has already been put in practical use in the Global System for Mobile communications (GSM) that is the cellular phone standard of Europe. Further, in the International Telecommunications Union (ITU), the standardization of a third-generation cellular phone system of which the target is the realization of cellular phone mobile units that mount the international roaming function and can be used in common in each country of the world is advancing.
When the international call between cellular phones is daily placed in this manner, it becomes very important information for the user or caller to know that the recipient is in which country and area now and what time the local time is. In particular, the cellular phone does not have any international long-distance telephone number identification part in a telephone number. Accordingly, when the user moves abroad or to an area of a different time zone with his or her cellular phone, it is very difficult to know the time at the place where the recipient exists, since the current position of the user cannot be known only from the telephone number of the cellular phone.